This invention relates to an end-effector for a robotic mechanism. More particularly, it relates to a scoop or bucket-like attachment for capturing and picking-up friable material, such as soil. It also relates to a versatile end-effector for grasping articles.
In the field of earth moving diggers, diggers have been provided with scooping shovels that have a bucket with a hinged bottom panel. The bottom panel closes up against the edges of the bucket to provide a floor for the bucket. This design was particularly common with steam-powered shovels and is still used in many petroleum-powered earth moving machines.
In designs based on a scoop having a shovel/bucket fixed to an arm with the floor panel being hinged, penetration of the scoop into soil has been effected by manipulation of the bucket through the supporting arm.
As well, shovel buckets have been attached to a supporting arm by hinged joints, with provision to actuate the bucket itself to perform claw-like functions. In this latter arrangement, the bucket is generally of a monolithic form i.e. the bottom panel and sidewalls are integral. In many configurations the jaws of a pair of such xe2x80x9cclamxe2x80x9d buckets close together until their teeth abut against each other.
In both of the described cases reliance is placed on the weight of the arm to break into material that is to be gathered. In earth-moving equipment, the weight of the arm is substantial and by merely dropping the arm under gravity, sufficient force can be applied to provide a penetrating effect.
In robotic applications wherein a vehicle is provided with an arm with a scoop to collect samples of material through remote actuation, the vehicle may not be of significant mass. Similarly, the arm may also be of light-weight. This is particularly true of extra terrestrial exploration vehicles that are necessarily of light weight in a low gravity environment.
A need exists for an end-effector arrangement based upon a light weight supporting arm that is nevertheless able to apply adequate disruptive breaking forces to material that is to be collected. Such an end-effector should be versatile in its capacity to gather and contain material being collected while nevertheless being relatively simple in design. As well, it would be desirable to enable such an end-effector to grasp articles that are adapted to be engaged by the end-effector. The present invention addresses these objectives
The invention in its general form will first be described, and then its implementation in terms of specific embodiments will be detailed with reference to the drawings following hereafter. These embodiments are intended to demonstrate the principle of the invention, and the manner of its implementation. The invention in its broadest and more specific forms will then be further described, and defined, in each of the individual claims which conclude this Specification.
According to one aspect of the invention an end-effector carried by a supporting arm is in the form of a bucket that has an actuated scoop as one portion and a non-actuated plate as a second portion. The scoop lacks an enclosing end wall and is defined instead by its side and circumferential wall only.
The plate, which is able to serve as a xe2x80x9cfloorxe2x80x9d for the bucket, is fixed to the arm at some convenient position. The scoop is manipulated by causing it to rotate towards, and preferably around the plate. To achieve this effect, the scoop is hinged to swing in an arcuate path that allows the scoop to be positioned so the plate serves as a xe2x80x9cfloorxe2x80x9d. The scoop may abut the plate, or pass around the plate with a sliding fit. The plate in this latter case serves as a partitioning wall inside a hinged, torus-like scoop segment that may be swung so as to envelop the plate.
As a preferred arrangement, the scoop can be arrested at a position whereat the plate serves as a floor portion at one end of the bucket. The scoop may also be arrested at a position wherein the plate is located intermediate the scoop""s front and back edges. Or it may be located at the other end of the scoop. In this manner a bucket cavity may be formed that opens outwardly in either of two, opposed directions.
The plate is carried by the arm, generally in a fixed orientation with respect to the arm. In use, the plate may be variously oriented horizontally or vertically by positioning of the arm. In one application the plate may be positioned so that it is substantially aligned with the supporting arm. Both of these components may then be placed in a vertical alignment and pressed into the ground in the manner of a spade.
Next, the scoop may first be elevated and then descended in an arc towards the plate. To the extent that material of the surface to be sampled lies above the lower edge of the plate, it will be severed from that surface upon which it lies and contained within the scoop. The scoop may then be closed to capture material which is located adjacent to the plate. Such material, e.g. soil, will then be contained by the circumferential, outer, curved surface of the scoop. The plate also serves to contain material in cooperation within the scoop, preventing it from falling out of the end of the scoop by closing-off one end of the scoop.
The plate may be attached to the supporting arm, at a fixed orientation, or its orientation with respect to the arm may be adjustable. It may also be controllable in the sense of being actuated. An adjustable coupling for the plate may be effected through use of a hinged connection to the arm that includes a locking system that will fix the plate at differing, xe2x80x9cindexedxe2x80x9d, orientations with respect to the arm. In an aligned orientation, the plate and arm can function as a xe2x80x9cshovelxe2x80x9d.
The plate need not be flat. It may be cylindrically curved, for example. The scoop, as well, need not be of circular cross-section. It is sufficient that the edges of the plate fit closely enough to the scoop to provide a containment function when they are interfitted with each other.
The plate and scoop may share a common hinge axis. Alternately, the plate may be separately mounted to the arm by supporting means that extends laterally past the hinge of the scoop to connect to the arm.
While the plate need not be actuated, it is intended that the circumferentially moving scoop be actuated. The scoop preferably may be swung in an arc about its axis that may extend up to nearly 360xc2x0 or more. In passing along this curved trajectory, the scoop is able to pass around the plate entirely. By arresting the scoop at appropriate locations with respect to the plate, a bucket cavity can be formed on either side of the plate portion.
In more secure operations where spillage is undesirable, a second partitioning panel, providing a second end-wall function to compliment the role of the plate, may be carried by the arm. Such second panel may be both hinged and actuated so as to, when closed on the scoop, form a fully contained cavity within the scoop. With such a cavity so formed, the supporting arm may convey the sampled material without the same orientation restraints that would be present if the bucket were open at one end. This type of arrangement is especially suited to the gathering of contaminating material which should not he dropped during transport.
By a further feature of the invention, the scoop and plate may adapted to provide a self-aligning, tool grasping interface allowing the grasping and constraining of articles. This may be effected by providing cooperating notches along the edges of the scoop and/or plate that are positioned to cooperate in engaging with articles that are to be grasped.
The foregoing summarizes the principal features of the invention and some of its optional aspects. The invention may be further understood by the description of the preferred embodiments, in conjunction with the drawings, which now follow.